Much of the water on Earth and elsewhere in the solar system likely predates the birth of the sun, a new study reports.
The finding suggests that water is commonly incorporated into newly forming planets throughout the Milky Way galaxy and beyond, researchers said — good news for anyone hoping that Earth isn’t the only world to host life.
“The implications of our study are that interstellar water-ice remarkably survived the incredibly violent process of stellar birth to then be incorporated into planetary bodies,” study lead author Ilse Cleeves, an astronomy Ph.D. student at the University of Michigan, told Space.com via email. [Theories on the Origin of Life]
“If our sun’s formation was typical, interstellar ices, including water, likely survive and are a common ingredient during the formation of all extrasolar systems,” Cleeves added. “This is particularly exciting given the number of confirmed extrasolar planetary systems to date — that they, too, had access to abundant, life-fostering water during their formation.”
Astronomers have discovered nearly 2,000 exoplanets so far, and many billions likely lurk undetected in the depths of space. On average, every Milky Way star is thought to host at least one planet.
Water, water everywhere
Our solar system abounds with water. Oceans of it slosh about not only on Earth’s surface but also beneath the icy shells of Jupiter’s moon Europa and the Saturn satellite Enceladus. And water ice is found on Earth’s moon, on comets, at the Martian poles and even inside shadowed craters on Mercury, the planet closest to the sun.
Cleeves and her colleagues wanted to know where all this water came from.
The Milky Way is part of a much vaster galactic network than previously thought. The galaxy drifts along in a stream of galaxies on the outskirts of a newly identified collection of galaxy clusters, a supercluster named Laniakea. This supercluster — whose name means “heaven immeasurable” in Hawaiian — holds the mass of 100 million billion suns within a region that spans about 520 million light-years.
Astrophysicist R. Brent Tully of the University of Hawaii in Honolulu and colleagues sifted through data describing the positions and velocities of over 8,000 galaxies to get a fresh look at the Milky Way’s place in space. After accounting for the motion caused by the expansion of the universe, the team created a three-dimensional view of how gravity molds the galaxy’s cosmic neighborhood.
The new map, published in the Sept. 4 Nature, reveals Laniakea’s boundaries and weblike framework. The Milky Way lies along one of the lines of that web, in a tributary feeding one of many galactic rivers. Those streams converge in a gravitational valley roughly 200 million light-years away near two massive galaxy clusters: Norma and Centaurus. Their combined gravity appears to be drawing in other galaxies and clusters within Laniakea, including the Milky Way.
Watch Laniakea Supercluster to see how the Milky Way fits into this complex network of galaxies.